Some electronic devices use rechargeable batteries that require periodic charging to maintain proper device performance. Battery rechargers typically require a battery to be inserted into the recharger in a single specific physical orientation to provide the correct polarity for recharging the battery. Existing solutions rely on either mechanical features to restrict the user from inserting the battery the wrong way or visible markings to instruct the user on proper insertion. However, these solutions are troublesome in the case of relatively small battery cells. Mechanical features can be defeated by forceful insertion, which can prevent battery charging or even cause damage to the battery or charger. Visible markings are often difficult to see, particularly if small and not high in contrast, and are ineffective for people with visual impairments.
Accordingly, there is a need in the art for improved apparatus and methods for detecting and switching battery polarity in a battery charger.